vanBassum
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Urea to Ammonia using urease
Hello,
Let me start off by saying that my knowledge of bio is just about enough to keep myself alive. So please bear with me. 
Every so often I have the urge to try and make nitric / nitrates. Last time I made platinum on quartz wool and used a pump to bubble air through an
ammonia solution. That worked, but doesn't seem very economical or practical. While I was looking around for possible candidates to convert into
nitrates, urea seems to be the most economical. Problem is, I need to convert the urea to ammonia. I have looked into thermal decomposition and a
process called eU2A that uses electrolysis. When using these methods, I soon found that the output of ammonia isn't steady enough to leave it running
for a couple of hours.
While searching the internet, I found that urea could be hydrolyzed to ammonia using an enzyme called urease. Apparently, this enzyme is found in
watermelon seeds. My idea is to get a watermelon and just try it out. (I mean, they are delicious, so win-win.) As a first test, I was thinking of
just crushing up some seeds and put them in a solution of water and urea. Then I hope to smell ammonia after a bit. If this works, I just pump air
through the solution, driving the ammonia / air mixture through the catalyst. I assume you need quite a lot to get a decent production of ammonia. I
was thinking of filling a 25L bottle. As a very nice bonus, the urea is converted into ammonia and CO2, so there won't be any products left after the
urea is depleted. It might be possible to just keep feeding the reaction more urea.
Now for my questions:
- Has anybody got experience using urease?
- How many seeds would I need per liter?
- Could the urease be isolated from the seeds?
- What concentrations of urea do I need?
- Is this a viable idea?
Sources:
- eU2A: https://iopscience.iop.org/article/10.1149/2.0041510eel
- Urease: https://microbiologyinfo.com/urease-test-principle-media-pro...
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Alkoholvergiftung
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I ve only read that before ww1 an Factory in Yokohama worked with urease and urin. They made ammonia in worth of 140Mark (that was an lot worth) a
day. The urease was form soya beans. Maybe you finde more with google.
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UC235
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Enzymes don't really work like that. They're generally quite slow relative to lab chemistry, they tend to die when their solutions are bubbled
(physical denaturation at the air/water interface), and typically require buffer solutions with pH control for activity. Without pH control,
formation of ammonia will rapidly raise pH and the enzyme stops working. It may even irreversibly denature it but that is enzyme specific
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Tsjerk
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Not to mention the effect of concentration of the product often effects the enzyme activity. When the concentration of ammonia/ammonia salts becomes
too high activity will drop.
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khlor
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I am not sure if it helps or if you are still on this project, but... here is my take on it, since in a not so near future I myself will be performing
experiments with a somewhat similar goal. so here is my shot:
Instead of bothering with enzymes which are slow and difficult to keep, why not do it with bacteria, I mean, there are plenty of bacteria that do
convert urea to ammonia, it is easy to take care of it and easy to scale up, as well as readily available from what I could gather, since it can be
found almost anywhere on the ground and air. I do believe that going this rout is far more feasible than dealing with enzymes.
please understand that I am not an expert, nor I did this before, just someone who does experiments on my spare time and I just happened to find this
thread.
best regards!
Khlor Ag.
"NOOOOOO!!! The mixture is all WROOOOOOONG!"
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Alkoholvergiftung
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Problem with Bacterias is Ammonia poisening. Ammonia oxidizing Bacterias life from ammonia but got poisenend if ammonia solution has more than 1,5%. I
think the same is for the Urea decompusers.
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khlor
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Quote: Originally posted by Alkoholvergiftung  | | Problem with Bacterias is Ammonia poisening. Ammonia oxidizing Bacterias life from ammonia but got poisenend if ammonia solution has more than 1,5%. I
think the same is for the Urea decompusers. |
I see, that makes sense, an embarassing oversight on my part. though, since you mention that, I believe it could still be used to make ammonia salts
which are easier to process into ammonia than urea, using an acid buffer solution to react with the ammonia as it is formed something like HCl, H2SO4
in low enough concentrations as not to upset the bacteria and then adding it continuously dropwise to keep enough acid to react with the newly formed
ammonia but not so much as to acidify the solution. however I don't know what would the maximum ammonia salts concentration the solution could hold
before it started affecting the bacteria.
just a theory I cooked up as I read your post, I know it is done in the industry to produce other goods and it is also done in the human body to keep
pH equilibrium so it could work on a bio-reactor even though it would be at the cost of simplicity(increasing complexity)
"NOOOOOO!!! The mixture is all WROOOOOOONG!"
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pesco
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If your goal are nitrates look at my post over here -> https://www.sciencemadness.org/whisper/viewthread.php?tid=16...
From experience with working with pure enzymes back at uni and bit afterwards I know it is often difficult, slow and expensive.
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